NASA's AIM [Aeronomy of Ice in the Mesosphere] spacecraft began its two-year mission April 25, 2007 after a flawless ride to Earth orbit aboard an Orbital Sciences Pegasus XL rocket. Launch took place at 1:26 PDT. Launch operations at Vandenberg Air Force Base in California ran smoothly, with no technical or weather issues causing concern. The AIM mission is the first dedicated to exploring mysterious ice clouds that dot the edge of space in Earth's polar regions. These clouds have grown brighter and more prevalent in recent years and some scientists suggest that changes in these clouds may be the result of climate change.